Radial type hydraulic pump



31, 1954v J. A. MORROW 2,687,615

RADIAL TYPE HYDRAULIC PUMP Filed Feb. 21, 1952 2 Sheets-Sheet l a? 10 8i z RETURN TO EUMP ACTUATE D H RETURN T0 SUMP MEfiHANISM TO BE J 2111A-MUI"Z"DW Aug. 31, 1954 J. A. MORROW RADIAL TYPE HYDRAULIC PUMP 2Sheets-Sheet 2 Filed Feb. 21, 1952 SPEED IN R.P.M.

J: Z121 MUUW PROGRESSIOO 0E PLUNGER IN ITS CYCLE Patented Aug. 31, 1954STA'EES PATENT OFFICE PADKAL TYPE HYDRAULIC PUMP Application February21, 1952, Serial No. 272,841

8 Giaims. l

This invention relates to hydraulic pumps and refers more particularlyto what might be characterized broadly as a radial type pump, butwherein the pumping action is derived not from the rotary movement ofvanes along with the rotor but rather from the successive radiallyinward depression of a series of radially disposed pistons or plungerscarried by the rotor.

In pumps of this type the pistons or plungers are slidably received inpockets formed in the rotor and project from the outer ends of thesepockets to bear against the inner cylindrical wall of a pumping chamberin which the rotor revolves eccentrically to the chamber. Ptadiallyoutward projection of the plungers draws the fluid to be pumped into theplunger pockets through an appropriately located inlet port and inwarddepression of the plungers expells the fluid from the pockets into adischarge port.

The patent of I. T. Dyer No. 559,534 illustrates a pump operating uponthis general principle.

Pumps which operate upon this principle have the advantage ofcompactness and comparative simplicity, but heretofore were not suitablefor service which requires a constant volumetric output despitesubstantial changes in the speed of the pump rotor. This condition ismet, for instance, in hydraulic boosters for the steering gears ofautomobiles and other vehicles where the pump which supplies thehydraulic pressure, being driven from the engine, varies in speedandruns at low speed when the need for the booster is greatest and at highspeed when little help is required from the booster.

This invention has as its purpose to adapt the so-called radial pump toservice such as that demanded by hydraulic steering boosters and thushas one of its objects to provide a pump of the chaarcter describedwhich has an effective output at a relatively low rotor speed and inwhich the output remains substantially constant over a wide range ofrotor speeds.

ihis result is achieved with the present invention by so balancing theforces acting upon the plungers or pistons that for a relatively widerange of rotor speeds the quantity of fluid drawn into the plungerpockets diminishes proportionately as the speed of the rotor rises sothat the pump has substantially the same volumetric output per unit oftime throughout the given range of rotor speeds.

With reduction in the size of the charges taken into the plungerpockets, the plungers, during part of their travel about their circularorbit, leave the cylindrical wall of the chamber against which theywould otherwise bear. Reengagement of the plungers with the circularchamber wall if it were allowed to be an abrupt impact could be a sourceof highly objectionable noise. In recognition of this undesirablepossibility this invention has as another of its objects to providemeans for assuring gradual and gentle re-engagement between the plungersand the cylindrical chamber Wall under all operating conditions.

With the above and other objects in View, which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiment of thehereindisclosed invention may be made as come within the scope of theclaims.

The accompanying drawings illustrate one complete example of thephysical embodiment of the invention constructed according to the bestmode so far devised for the practical application of the principlesthereof, and in which:

Figure l is a cross sectional view through a pump embodying thisinvention, said view being.

taken on the plane of the line l-l of Fi ure 2;

Figure 2 is a longitudinal sectional view through the pump taken on theplane of the line 2?. in Figure 1;

Figure 3 is a perspective view of the pump rotor and one or" itsplungers;

Figure 4 is a perspective view of the elements of the pump casing shownseparated but in their proper order of assembly;

Figure 5 is an enlarged view more or less diagrammatically illustratingthe progression of motion of one plunger in its pumping cycle at a rotorspeed at which the plunger is not projected its full distance; and

Figure 6 is a chart generally illustrating the volumetric output of thepump at different rotor speeds.

Referring now particularly to the accompanying drawings in which likenumerals indicate like parts, the numeral 1 designates the casing of thepump which may, of course, be constructed in any suitable manner but inthe present instance comprises an annular midsection 8 and two disc-likeend sections 9 and It, the three sections being held together by capscrews II. This casing definesa cylindrical chamber having a cylindricalwall [2 and flat end Walls l3 and M Within the cylindrical chamber is arotor l5 keyed to a drive shaft IS. The shaft I6 is journalled incoaxial bearings I1 and la in the end sections 53 and H], respectively,and so disposed with respect to the axis of the cylindrical chamber thatthe rotor revolves eccentrically thereto. As a result the radialdistance between the rotor axis and the cylindrical wall |2 increasesfor half a rotor revolution and decreases during the other half.

If the pump is used to supply hydraulic pressure to a steering gearbooster on an automobile the drive shaft l6 which protrudes from thecasing through an appropriate oil seal I8 is drivingly connected to asuitable power takeoff shaft on the automobile engine (not shown) Thesides of the rotor l have a close runmng fit with the fiat end walls l3and I4 and a plurality of equiangularly spaced plun er pockets l9, fourin the present case, are formed in the rotor. These pockets open to theopposite sides of the rotor as well as to its outer periphery and withineach is a plunger 2|! of a size and shape to have a snug sliding fit notonly with the opposite side walls of the pocket but also with the flatend walls I3 and I4.

Attention is directed to the fact that there are no springs to urge theplungers 20 one way or the other, Hence, the plungers are free torespond to centrifugal force as the rotor revolves and by it to bethrown radially outward to bear against the cylindrical wall l2. Exceptfor the restraining forces to be later discussed the plungers would,therefore, retain contact with the wall l2 as long as the rotor wasrevolving and by virtue of the eccentricity of the rotor and chamher,would move radially outward during half a revolution of the rotor andradially inward during the other half.

During that half of the rotary orbit of a plunger when it is movingradially outward oil or other fluid being pumped is drawn into the innerend portion of the plunger pocket by virtue of the communication betweenthe pocket and an arcuate feed port 2| in one end wall of the chamber,in this instance in the wall [3. This arcuate feed port, which is merelya groove in the wall I3, has an inlet passage 22 leading thereto and aninlet pipe 23 connects the passage 22 with the source of oil or otherfluid to be pumped (not shown).

It is, of course, necessary that the arcuate feed port 2| be so locatedwith respect to the circular orbit of the plungers as to be swept by thinner end portions of the plunger pockets during that half of theplunger orbit, or at least a substantial portion thereof, when theplunger is moving radially outward. Hence, the arcuate feed port 2| isconcentric to the rotor axis.

The fluid drawn into the plunger pockets in consequence to the radiallyoutward projection of the plungers as they sweep along the feed port 2|is discharged from the pockets into an arcuate discharge port 24 formedin one or the other of the two fiat side walls of the chamber (the wallI 3 in this case) and connected with an outlet passage 25. A pipe 26leads from the outlet passage 25 to the mechanism to be actuated,diagrammatically illustrated in the drawings by an appropriate legend.

The manner in which the plunger pockets are communicated with thedischarge port 24 which, like the port 2 I, is an arcuate groove in thewall I3, is of importance particularly from the standpoint of assuringquiet operation. It will be noted that each plunger is provided with acavity 21 which opens through a port 28 to at least that side of theplunger which is contiguous to the wall IS in which the arcuate feed anddischarge ports are located, though for convenience in production theport 28 may pass entirely through the plunger. The cavity 2'! also opensto the inner end of the plunger through a port 29. Between the port 28and the interior of the cavity is a valve seat 30 upon which a ballcheck valve 3| normally seats, being spring urged into engagementtherewith.

The check valve 3| thus closes radially inward and opens radiallyoutward. Outward radial projection of the plunger to draw in a charge offluid from the feed port 2|, therefore, does not affect the seatedcondition of the valve but radially inward depression of the plunger toexpel the fluid from under it opens the valve to allow the fluid underthe plunger to escape through the open valve and the port 28 into thegroove 24 and thence to the mechanism to be actuated.

This manner of expelling the fluid from the plunger pockets, of course,requires the discharge port 28 of the plungers to align with the arcuateport 24 throughout the entire time that a plunger is being depressed.Accordingly the arcuate port 24 is concentric to the cylindrical wall i2of the pump chamber, so that if the plunger is fully projected as is thetop plunger of Figure 1, its port 28 aligns with the outermost end 24'of the arcuate groove 24 as soon as the plunger comes opposite it andremains in alignment with the arcuate groove throughout the entiredepression of the plunger.

On the other hand, if the plunger is not fully .projected the operationis as illustrated in Figure 5 which shows the progression of positionsoccupied by one plunger during one complete cycle. As here shown theport 28 is radially inward of the outermost end 24' of the arcuategroove or port 24 and does not begin to communicate with the port 24until a position A is reached approximately fifty degrees to the left ofvertical. However, although the port 23 aligns with the arcuate groove24 at this point in the cycle there is no communication between thegroove or port 24 and the plunger pocket beneath the plunger until theball check valve is unseated and the valve will not unseat until radialinward depression of the plunger begins.

Consequently, as distinguished from what would be the case without theball check valve, the plunger remains in its partially projectedposition and does not fly out to impinge the cylindrical chamber wall I2the instant back pressure in the port is manifested at the plunger port28. As a result the plunger gradually and gently contacts thecylindrical chamber wall l2 between its positions A and B and upon suchcontact radial inward depression of the plunger begins. As soon as suchinward depression is begun the ball check valve is unseated and thefluid under the plunger is forced out of the plunger pocket into thedischarge port 24 and hence to the mechanism to be actuated.

The spent fluid leaving the mechanism to be actuated could, of course,be conducted directly to the sump from which the pump draws its supplybut instead the pressure remaining in the returning fluid is put touseful purpose by returning at least a part thereof through the pumpchamber by way of a shunt line 32, the amount so by-passed dependingupon the setting of a control valve 32 in the return to the sump. The

pipe line 32 connects with a passage 33 formed in one of the two endsections of the housing and opening into the hollow pump chamber at apoint near its periphery.

From the pump chamber a passage 34 and .a pipe line 35 carries thereturning fluid back to the sump. This return line is preferablyequipped with a throttling valve 35' so that by coordinated adjustmentof the valves 32' and 35' practically any desired pressure condition canbe established in the pump chamber. The pressure in the pump chamber is,of course, also a function of the speed of the rotor-the higher thespeed the greater the pressure in the chamber and vice versa. Hence, theextent to which the pressure in the pump chamber resists the outwardprojection of the plungers by centrifugal force is self compensating.

To augment the hydraulic pressure within the pump chamber resulting fromits connection to the return line for the spent fluid, the points ofcommunication between the passages 33 and 3 with the chamber are solocated that at high speeds when the plungers do not make their fullstroke the path of the plunger past the mouth of the passage 33 isradially inward therefrom so as not to interfere with the inflow offluid whereas the location of the mouth of the passage 34 being close tothe periphery of the rotor is always in the path of the plungersregardless of their positions in the pockets. The plungers sweepingacross the mouth of the passage 34 with increasing rapidity as the speedof the rotor rises, thus more and more interfere with the discharge ofthe fluid from the pump chamber and thus produce a desirable shutteringeffect which augments the hydraulic pressure within the chamber.

Pressurizing of the pump chamber supplies one of the forces resistingthe centrifugal force acting upon the plungers. The other force whichacts against centrifugal force and thus combines with the pressure inthe pump chamber is suction under the plungers which results from theorifice effect of the feed port 2|.

The outward projection of the plungers in response to centrifugal forcedraws fluid into the plunger pockets but the size of each charge or, inother words, the quantity of fluid thus drawn into the plunger pocketsdepends upon the relative magnitude of all of the forces acting on theplungers and, as has been shown, all of these forces are functions ofthe speed of the rotor. It follows, of course, that the volume of fluiddischarged by the pump can be no greater than that taken into theplunger pockets, hence if these various contending forces arepredetermined to decrease the size of the charge drawn into the plungerpockets as the rotor speed rises, a substantially uniform dischargevolume can be maintained over a relatively wide speed-range. The desiredbalance between the forces acting on the plungers is readily eiiected bycontrolling the volume of fluid returned through the pump chamber andregulating the constricting effect of the feed port 2! according to theweight of the plungers.

With these control factors properly adjusted or predetermined almost anyperformance requirements can be met. Thus, as illustrated in the curveof Figure 6, the volumetric output of the pump can be made to riserelatively abruptly during an initial rise in rotor speed, and thenremain substantially constant for a substantial range of increasingspeeds. The final upturn of the curve results from the centrifugal forceoverbalancing the opposing forces.

Attention is directed to the specific shape of the plungers. Theirnarrow outer ends 20 not only reduce the weight of the plungers andhence diminish the effect of centrifugal force thereon, but in additionhave the advantage of reducing the throttling effect upon the inflow ofthe hydraulic fluid into the pump chamber at the time when the plungersare fully projected and thus sweep across the mouth of the inlet passage33. At least the throttling or metering effect upon the inflow is not asgreat as it is upon the discharge of the fluid from the chamber. Theholes 36 through the outer thin ends of the plungers are for the purposeof minimizing the turbulence within the pump chamber.

By virtue of the fact that the sides of the rotor have a close runningfit with the flat end walls [3 and I l, the loss of pressure by leakageout of the plunger pockets is extremely slight but some fluid inevitablywill enter the clearance between the sides of the rotor and the endwalls l3 and I 4 and to equalize the pressure at both sides of the rotorand thus assure smooth operation the wall I4 preferably has an arcuateoil groove 31 formed therein.

From the foregoing description taken in connection with the accompanyingdrawings, it will be readily apparent to those skilled in this art thatthis invention, though it deals with a relatively old form of pump, hasmany advantages especially since it adapts the so-called radial typepump to service which requires substantially uniform volumetric outputover a relatively wide range of rotor speed.

What I claim as my invention is:

1. A radial type pump of the character described wherein a rotorrevolves eccentrically within a bore, the wall of which is fixed withrespect to the rotor axis and wherein the rotor has plungers slidable inradial pockets in the rotor so that by their orbital travel around thewall of the bore, the plungers alternately move outwardly to draw fluidthrough the pump inlet and into their pockets and then move inwardly toexpel such fluid from their pockets and through the pump outlet:characterized by the provision of means to increasingly resist outwardmovement of the plungers as the speed of the rotor increases and therebylimit their outward movement to progressively less then their fullstroke as defined by the eccentricity of the bore with respect to therotor axis, so that the amount of fluid drawn into each plunger pocketdecreases as the speed of the rotor increases and substantially uniformvolumetric output for the pump is maintained over a relatively widerange of rotor speeds, said means comprising walls embracing the rotorand cooperating with the wall of the bore in which the rotor revolves todefine a closed chamber into which the outer ends of the plungersproject, and means to subject the interior of said chamber to a fluidpressure which increases as the speed of the rotor increases.

2. The radial pump set forth in claim 1 further characterized by thefact that the means for subjecting said chamber to pressure includescontrol means for regulating the pressure in said chamber and fordetermining the minimum rotor speed at which such pressure becomeseffective to limit outward movement of the plungers.

3. The radial pump set forth in claim 1 further characterized by thefact that the fluid pressure manifested in said chamber is derived fromthe pump outlet and thus increases substantially proportionately to thespeed of the rotor.

4. The radial pump set forth in claim 3 further characterized by theprovision of duct means conmeeting the pump outlet with said chamberthrough a mechanism to be actuated by the fluid pressure developed inthe pump so that the pressure manifested in said chamber is thatobtaining at the outlet side of said mechanism to be actuated.

5. The radial pump set forth in claim 4 further characterized by theprovision of exhaust duct means leading from the fluid outlet of themechanism to be actuated; and control means comprising a restriction insaid exhaust duct means downstream from the point of communicationbetween said chamber and the fluid outlet of the mechanism to beactuated, said control means regulating the pressure in said chamber anddetermining the minimum rotor speed at which such pressure becomeseffective to limit outward movement of the plungers.

6. The pump defined in claim 1 further characterized by the provision ofmeans for preventing sudden and forcible impingement of partiallyprojected plungers against the wall of the bore by back pressure at theoutlet port of the pump greater than the pressure in said closed chamberinto which the outer ends of the plungers project and manifested in thepockets of said plungers as they are brought into communication with theoutlet port, said means comprising check valve means controllingcommunication between the plunger pockets and the outlet port arrangedto be closed by back pressure at the outlet port.

7. The pump as defined in claim 6 further characterized by the fact thatcommunication between each plunger pocket and'the outlet port of thepump is through a passage in its plunger; and further by the fact thatsaid check valve means comprises a check valve located in said passageof each of the plungers.

8. A radial type pump of the character described wherein a rotorrevolves eccentrically within a bore, and wherein the rotor has plungersslidable in radial pockets in the rotor so that by movement around thewall of the bore each plunger alternately moves outwardly to draw fluidthrough the pump inlet and into its pocket and then moves inwardly toexpel such fluid from the pocket and through the outlet port of thepump; characterized by the fact that communication between each pocketand the outlet port of the pump is through a passage in its plunger; andfurther characterized by the provision of means for preventing suddenand forcible impingement of a partially projected plunger against thewall of the bore by back pressure at the outlet port manifested in thepocket of such partially projected plunger as said pocket is broughtinto communication with the outlet port, said means comprising a checkvalve located in the passage of each plunger and arranged to be closedby back pressure at the .outlet port.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,358,454 McLeod Nov. 9, 1920 1,485,986 Magie et a1 Mar. 4,1924 1,641,509 Stewart Sept. 6, 1927 1,738,375 Landenberger et a1. Dec.3, 1929 2,137,448 Ernst Nov. 22, 1933 2,335,284 Kendrick Nov. 30, 19432,454,563 Mercier Nov. 23, 1948 2,461,235 Raymond Feb. 8, 1949 2,528,739Carey Nov. 7, 1950 2,545,238 MacMillin et al Mar. 13, 1951 2,599,609Carey June 10, 1952 FOREIGN PATENTS Number Country Date 492,463 GreatBritain Sept 21, 1938

